PORTLAND, Ore. – The U.S. attorney for Oregon has served notice on all medical marijuana growers, saying the federal government will not allow the sale of pot anywhere in Oregon.

U.S. Attorney Dwight Holton issued the warning not only to growers but to landlords, saying "Knowingly financing a marijuana dispensary or allowing one to operate on your property also violates federal law and could subject financier and landlords to civil and criminal penalties."

There are dozens of growers markets across the state. But many patients and growers are adamant these are farmers markets or grower co-ops and not dispensaries. They say there is never a free exchange of money for marijuana at these operations. They also say they believe it is just another assault on the medical marijuana law passed by Oregon voters.

During a Friday at a strip mall on Southeast 82nd, Oregon medical marijuana patients went into an office and came out with paper bags containing jars of pot.

Medical marijuana patients who use the facility say it's not a dispensary. It’s a farmers market. They make a donation and for that donation they are given a playing card. They then give the playing card to a medical marijuana grower. They may get a jar of medical marijuana or not. There is no quid pro quo – no guarantee they will get marijuana for their money.

For that reason users and operators say they do not believe they are violating laws because they are not actually buying or selling pot.

Bill Elliott, a 65-year-old Vietnam veteran, has been a medical marijuana cardholder for almost three years. He doesn't get his marijuana at that office but he manages the nearby Cannabis Café and knows a lot of people who do get their marijuana there.

"If we don't have any clear-cut decisions or clear-cut guidelines about what they are defining as dispensaries and what they are defining in terms of what we define as a farmers market – yeah, we could find some gray areas that could cause us some problems," he said.

He says he would like guidance from his government, not threats for doing what he believes is his legal right as an Oregonian.

The National Organization for the Reform of Marijuana Laws (NORML) sees it the same way.

"They're not allowed to try to find medical marijuana except on the black market. And so this type of behavior and law enforcement with the heavy hand is just pushing people out to the black market," she said. "Instead, what the government should do is try to capture that revenue and put it into our state coffers."

Whether they are called dispensaries or growers markets, patients and supporters of legalization of marijuana say the same thing: These facilities drive illegal black market dope dealers out of business, because the dealers can’t compete with the small donation prices made to markets.